Silane-modified phenolic resins and applications thereof

ABSTRACT

A silane-modified phenolic resin is prepared by reacting a phenolic compound (e.g., resorcinol) with an aldehyde to produce a phenolic novolak resin. The phenolic novolak resin is further reacted with at least one silane compound to produce the silane-modified phenolic resin. The reaction is typically carried out in the presence of an acid or base catalyst. The resulting resin has a lower softening point and can be used as a methylene acceptor compound in a vulcanizable rubber composition.

PRIOR RELATED APPLICATIONS

[0001] Not applicable.

FEDERALLY SPONSORED RESEARCH STATEMENT

[0002] Not applicable.

REFERENCE TO MICROFICHE APPENDIX

[0003] Not applicable.

FIELD OF THE INVENTION

[0004] The invention relates to silane-modified phenolic resins, methodsfor their synthesis, and applications thereof, especially in reinforcedrubber compositions.

BACKGROUND OF THE INVENTION

[0005] Rubber articles, such as tires, belts and hoses, normally usereinforcing materials such as steel, polyester, nylon, aramid and rayonin the form of fibers, cords or fabrics. In the case of radial tireproduction, steel cords are often used as the reinforcing material.Steel cords for tires, in general, are coated with a layer of brass topromote adhesion between the steel cords and rubber compounds. In orderto improve the adhesion between rubber and steel cords, the use of acobalt salt, such as cobalt naphthenate, and/or a phenolic adhesivecomposition comprising a methylene acceptor and methylene donor in thecompound formulations are in current practice. The copper and zincpresent in the brass coating react with sulfur to form a bonding layer,comprising sulphides of copper and zinc, between the steel cord andrubber. The formation of such sulfide layers at the interface isresponsible for the initial unaged adhesion of brass plated steel andrubber. The use of cobalt salt regulates the formation and compositionof copper sulfide and zinc sulfide layers. It has become common to useresorcinol or resorcinolic novolak resins as the phenolic methyleneacceptor and hexamethoxymethylmelamine (HMMM) orpentamethoxymethylmelamine (PMMM) as the methylene donor in rubbercompounds to improve the steel cord adhesion. On curing, the reactionproduct of phenolic methylene acceptor and donor form a protectivemoisture resistant resin coating on the bonding layer and protects theloss of adhesion during aging.

[0006] Achieving higher levels of steel cord adhesion with rubbercompounds and maintaining this adhesion under various environmentalconditions, such as heat, humidity and saline conditions, are importantfor the long term durability of tires. In the case of an unagedcondition, rubber-brass adhesion exceeds the tear strength of the rubberand therefore, no bond failure occurs at the copper sulfide and rubberinterface. But, under wet and salt water conditions the adhesion ofsteel cords fails due to corrosion. Though the cobalt salt was effectiveagainst salt water and steam-aged adhesion, the use of resorcinol orresorcinolic novolak resins, along with HMMM, has provided the highestadhesion under these conditions.

[0007] The corrosion of steel cords is due to the attack of moistureunder hot and wet conditions. If this is prevented, then the corrosionof steel wire can be avoided, thereby the adhesion level can bemaintained under all aged conditions of the tire. In this way theservice life of the tire can be extended.

[0008] In order to avoid or minimize the steel tire cords corrosion,several approaches or methods were employed, not only in the rubbercompound formulations but also with the treatment of steel cords.

[0009] In one method, steel wires were cleaned first and then coatedwith an amino-silane primer. Then the silane coated wires were againcoated with a phenol-resorcinol-formaldehyde-latex solution before beingincorporated into the rubber compound and cured. This method improvedthe hydrolytic stability of the bond between the steel and rubber.

[0010] In another method, the humidity-aged adhesion of brass platedsteel cord to rubber was improved by dipping the cord in dilute aceticacid in methanol solution followed by a treatment with H₂S gas. The cordwas then combined with a vulcanizable rubber compound and cured.

[0011] Bright steel wires dipped in the adhesive compositions preparedby the mixing of phenol-formaldehyde resole and resorcinol-formaldehydenovolak solutions showed a dramatic improvement over the brass platedwires in the adhesion retention after humidity aging. The highlycross-linked phenol-resorcinol-formaldehyde network formed from theresole and novolak that coated the bright steel is responsible for themoisture resistance and improving the humidity-aged adhesion.

[0012] Improved humidity-aged adhesion between a rubber compound andbright steel was achieved when the bright steel wires were dipped firstinto an alcoholic solution of aminosilanes and then vulcanized with arubber containing a phenolic novolak resin. Compared to brass-platedsteel cords, the silane-treated bright steel wires retained their highadhesion values after humidity aging.

[0013] The application of silanes and hydrolyzed silanes on the surfaceof reinforcing tire cords such as stainless steel, galvanized steel,tin, zinc or brass plated steel are known to prevent the corrosion ofthese metals. On hydrolysis, these silanes produce silanol groups whichare active towards the hydroxyl or oxide groups present on the surfaceof these metals. The silanol groups react themselves producing Si—O—Sibonds on the metal surface and are more stable and hydrophobic. Thismakes the silane-treated metal surfaces more resistant to moisture andcorrosive attack. Though this method provides a solution to prevent thecorrosion of steel cords, the use of highly flammable solvents todissolve these silanes, their applications onto these metal surfaces,and handling thereof can be an environmental hazard.

[0014] Therefore, there is a need for a new phenolic resin that can behandled and used relatively safely in rubber compound formulations and,in the meantime, improves the unaged, heat-, and humidity-aged adhesionof a brass-plated steel cords to cured rubber compounds.

SUMMARY OF THE INVENTION

[0015] The aforementioned need is fulfilled by various aspects of theinvention. In one aspect, the invention relates to a silane-modifiedphenolic resin prepared by a process comprising reacting a phenolicnovolak resin with a silane or a mixture of silane compounds. Suchsilane compounds are represented by Formula (C), (D), or (E):

[0016] wherein R₆, R₇ and R₈ are independently an alkyl group of 1 to 4carbon atoms, an alkoxy group of 1 to 8 carbon atoms, phenyl group, orcycloalkyl group; R₉ is a divalent saturated or unsaturated aliphaticstraight or branched hydrocarbon group with 1 to 12 carbon atoms; X is athiol, isocyanato, urea or glycidylether group; Z is S_(x) or an NHgroup wherein x is 1, 2, 3, 4, 5, 6, 7, or 8; and R₁₀ is a vinyl groupor an alkoxy group. In some embodiments, no substantial amount ofsiloxane polymer is formed during the reaction to make thesilane-modified phenolic resin. In other embodiments, thesilane-modified phenolic resin is substantially free of cross-linking.In some embodiments, the ratio of the number of equivalents of alkoxygroups in the silane compound to the number of equivalents of phenolichydroxyl groups in the phenolic novolak resin is less than 1, less than0.1, or less than 0.01. In other embodiments, the silane-modifiedphenolic resin is not further hydrolyzed.

[0017] The phenolic novolak resin is obtained by reacting one or morephenolic compounds represented by formula (A) with one or more aldehydeor ketone compounds:

[0018] wherein R₁, R₂, R₃, R₄ and R₅ represent independently an organicgroup selected from hydrogen, hydroxyl, an alkyl having 1 to 15 carbonatoms, an aralkyl of having 8 to 12 carbon atoms, halogen, or an aminogroup. For example, the phenolic compound can be a phenol, alkylsubstituted phenol, aralkyl substituted phenol, or a mixture of phenoland alkyl or aryl substituted phenol. It can also be a resorcinol oralkyl substituted resorcinol or an aralkyl substituted resorcinol.Examples of the aldehyde include, but are not limited to, formaldehyde,acetaldehyde, propionaldehyde, butyraldehyde, iso-butyraldehyde,n-valeraldehyde, benzaldehyde, crotonaldehyde, cinnamaldehyde, ormixtures thereof.

[0019] Examples of the phenolic novolak resin include, but are notlimited to, phenol-formaldehyde novolak, phenol-alkylphenol-formaldehydenovolak, phenol-aralkylphenol-formaldehyde novolak, high orthophenol-formaldehyde novolak, phenol-resorcinol-formaldehyde novolak,alkylphenol-resorcinol-formaldehyde novolak,aralkylphenol-resorcinol-formaldehyde novolak, resorcinol-formaldehydenovolak, alkylresorcinol-formaldehyde novolak,alkylresorcinol-resorcinol-formaldehyde novolak,aralkylresorcinol-resorcinol-formaldehyde novolak, and mixtures thereof.

[0020] Examples of suitable silanes include, but are not limited to,3-(aminopropyl)-triethoxysilane, 3-(isocyanatopropyl)triethoxysilane,3-(glycidyloxypropyl)trimethoxysilane,3-(mercaptopropyl)trimethoxysilane,N-beta-aminoethyl-3-(aminopropyl)trimethoxysilane,3-(aminopropyl)trimethoxysilane, 3-(aminoethyl)triethoxysilane,3-(glycidyloxyethyl)-triethoxysilane, 3-(mercaptopropyl)triethoxysilane,N-beta-aminoethyl-3-(aminoethyl)-trimethoxysilane,3-(aminobutyl)triethoxysilane, 3-(aminoethyl)trimethoxysilane,3-(aminopropyl)methyldiethoxysilane, N-(3-(triethoxysilyl)propyl)urea,3,3′-bis(trimethoxysilylpropyl)disulfide,3,3′-bis(triethoxysilylpropyl)tetrasulfide,3,3′-bis(trimethoxysilylpropyl)tetrasulfide,2,2′-bis(triethoxysilylethyl)tetrasulfide,3,3′-bis(trimethoxysilylpropyl)trisulfide,3,3′-bis(triethoxysilylpropyl)trisulfide,3,3′-bis(trimethoxysilylpropyl)hexasulfide,3,3′-bis(trimethoxysilylpropyl)octasulfide,3,3′-bis(trioctoxysilylpropyl)tetrasulfide,3,3′-bis(trihexoxysilylpropyl)disulfide, bis-silyl-aminosilanes,vinylmethyldiethoxysilane, vinylmethyldimethoxysilane,vinyltriethoxysilane, vinyltributoxysilane, vinyltriisopropoxysilane,vinyltriisopropenoxysilane, vinyltrimethoxysilane,vinyltriphenoxysilane, vinyltris(2-methoxyethoxy)silane,vinyldimethylethoxysilane, or mixtures thereof.

[0021] In another aspect, the invention relates to a rubber compoundingagent based on the silane-modified phenolic resin described herein.Accordingly, a vulcanizable rubber composition can be made thatcomprises (a) a rubber component, (b) a methylene donor compound whichgenerates formaldehyde by heating; and (c) a methylene acceptorcomprising a silane-modified phenolic resin obtained by the processcomprising reacting a phenolic novolak resin with a silane or a mixtureof silane compounds represented by Formula (C), (D), or (E). In someembodiments, the silane-modified phenolic resin is not substantiallycross-linked before the rubber composition is vulcanized. In otherembodiments, no substantial amount of siloxane polymer is formed duringthe reaction to produce the silane-modified phenolic resin. In someembodiments, the rubber component is selected from natural rubber,styrene-butadiene rubber, butadiene rubber, isoprene rubber,acrylonitrile-butadiene rubber, chloroprene rubber, butyl rubber,halogenated butyl rubber, ethylene-propylene-diene monomer (EPDM)rubber, or mixtures thereof. In other embodiments, the vulcanizablerubber composition further comprises a reinforcing material selectedfrom steel, polyester, nylon, aramid, fiberglass, or a combinationthereof. Moreover, the reinforcing material can be a steel cord coatedby brass, zinc or bronze. A fabricated article comprising thevulcanizable rubber composition can be made. For example, the fabricatedarticle can be a tire, a power belt, a conveyor belt, a printing roll, arubber shoe heel, a rubber shoe sole, an automobile floor mat, a truckmud flap, or a ball mill liner.

[0022] In yet another aspect, the invention relates to a method ofmaking a fabricated rubber article. The method comprises (1) obtaining avulcanizable rubber composition as described above mixed with across-linking agent; (2) embedding a reinforcing material in thevulcanizable rubber composition; and (3) effecting cross-linking of therubber composition, wherein the reinforcing material is embedded in therubber composition before the cross-linking and is substantially free ofa silane coating before the embedding. The reinforcing material can be,for example, steel, polyester, nylon, aramid, fiberglass, and acombination thereof and be in the form of wire or cord.

[0023] Additional aspects of the invention and advantages andcharacteristics provided by various embodiments of the invention becomeapparent with the following description.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0024] In the following description, all numbers disclosed herein areapproximate values, regardless whether the word “about” or “approximate”is used in connection therewith. They may vary by 1 percent, 2 percent,5 percent, or, sometimes, 10 to 20 percent. Whenever a numerical rangewith a lower limit, R^(L) and an upper limit, R^(U), is disclosed, anynumber falling within the range is specifically disclosed. Inparticular, the following numbers within the range are specificallydisclosed: R=R^(L)+k*(R^(U)−R^(L)), wherein k is a variable ranging from1 percent to 100 percent with a 1 percent increment, i.e., k is 1percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent,51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98percent, 99 percent, or 100 percent. Moreover, any numerical rangedefined by two R numbers as defined in the above is also specificallydisclosed.

[0025] Embodiments of the invention provide a silane-modified phenolicresin for use as a rubber compounding agent and a number of otherapplications. The silane-modified phenolic resin can be made by reactinga phenolic novolak resin with a silane or a mixture of silane compounds.In some embodiments, the resulting silane-modified phenolic resins isnot substantially cross-linked after the reaction. By “not substantiallycross-linked,” it is meant that the degree of cross-linking is less than10%, preferably less than about 5%, less than about 3%, or less thanabout 1%. The degree of cross-linking refers to the weight percentage ofthe gel (i.e., the insoluble portion in a chosen solvent) in a resin. Inother embodiments, the silane-modified phenolic resin is substantiallyfree of any siloxane polymer after the reaction. In other words, nosubstantial amount of siloxane polymer is formed during the reaction.

[0026] Phenolic novolak resins are polymeric materials and are made byheating a phenolic compound with a deficiency of an aldehyde or ketone,often in the presence of an acidic catalyst (such as oxalic acid orsulfuric acid). Generally, phenolic novolak resins are not cross-linked.Therefore, it is desired that the aldehyde/phenolic compound mole ratiobe less than one, otherwise cross-linking and gelation will occur duringmanufacture. Phenolic novolak resins generally comprise no methylolfunctionality, have molecular weights in the range of from about 125 toabout 5000, and display glass transition temperatures in the range offrom about 45° C. to about 100° C. Phenolic novolaks do not condensefurther by themselves unless additional aldehyde or other reactivematerials, i.e., formaldehyde donors such as hexamethylenetetramine, areadded.

[0027] Suitable phenolic compounds that can be used to make the phenolicnovolak resin are represented by Formula (A) as follows:

[0028] wherein R₁, R₂, R₃, R₄ and R₅ represent independently an organicgroup selected from hydrogen, hydroxyl, an alkyl having 1 to 15 carbonatoms, an aralkyl of having 8 to 12 carbon atoms, halogen, or an aminogroup. In Formula (A), R₁, R₂, R₃, R₄ and R₅ is designated as “R₁₋₅”.However, it should be understood that R₁, R₂, R₃, R₄ and R₅ canindependently be the same or different as defined above. Suitablephenolic compounds include, but are not limited to, phenol, substitutedphenol, resorcinol, or substituted resorcinol. Therefore, the term“phenolic novolak resin” encompasses not only novolak resins based onphenol (both substituted and unsubstituted), but also those based onresorcinol (both substituted and unsubstituted).

[0029] In accordance with Formula (A), the phenolic compounds suitablefor the preparation of phenolic novolak resins include, but are notlimited to, mononuclear phenols with an aromatic nucleus to which atleast one hydroxyl group is attached. Examples of mononuclear phenolsinclude, but are not limited to, phenol itself, homologues of phenolsuch as o-cresol, m-cresol, p-cresol, o-phenylphenol, p-phenylphenol,3,5-xylenol, 3,4-xylenol, 3-ethylphenol, 3,5-diethylphenol,p-butylphenol, 3,5-dibutylphenol, p-amylphenol, p-cyclohexylphenol,p-octylphenol, p-nonylphenol, styrylphenol, 3,5-dicyclohexylphenol,p-crotylphenol, 3,5-dimethoxyphenol, 3,4,5-trimethoxyphenol,p-ethoxyphenol, p-butoxyphenol, 3-methyl-4-methoxyphenol, aminophenol,and p-phenoxyphenol. Moreover, suitable phenolic compounds furtherinclude, but are not limited to, derivatives of dihydroxy benzene andpolyhydroxy benzenes, such as resorcinol, phloroglucinol, pyrogallol,5-methylresorcinol, 5-ethylresorcinol, 5-propylresorcinol,2-methylresorcinol, 4-methylresorcinol, 4-ethylresorcinol, and4-propylresorcinol. Suitable substituted resorcinol compounds include,but are not limited to, alkyl substituted resorcinol, aralkylsubstituted resorcinol, or a combination of both. Examples of suitableresorcinol derivatives are disclosed in U.S. Pat. No. 4,892,908; U.S.Pat. No. 4,605,696; U.S. Pat. No. 4,889,891; and U.S. Pat. No.5,021,522, which are incorporated by reference herein in their entirety.Furthermore, mixtures of aldehyde-reactive phenols, such as mixed cresolisomers, xylenols and phenolic blends such as those obtained from coaltar fractionation and cashew nut shell liquid, can be employed as all orpart of the phenolic compound. Multiple ring phenols such as bisphenol-Atypes are also suitable.

[0030] In some embodiments, at least two phenolic compounds are used.For example, the first phenolic compound can be phenol or substitutedphenol; the second phenolic compound can be resorcinol or substitutedresorcinol. In some instances, the first and second phenolic compoundsare phenol or substituted phenol, provided that the two compounds aredifferent. In other instances, the first and second phenolic compoundsare resorcinol or substituted resorcinol, provided that the twocompounds are different. Examples of such combination include, but arenot limited to, phenol/t-octyl phenol; phenol/resorcinol; phenol/cresol;p-butylphenol/phenol; cresol/resorcinol, etc.

[0031] Suitable aldehydes for reaction with a phenolic compound includeany aldehyde capable of such reaction. One class of such aldehydes isrepresented by formula: R—CH═O, wherein R is an alkyl, aryl, or aralkylhaving 1-20 carbon atoms per group. For example, R can be methyl, ethyl,propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, octyl,nonyl, decyl, benzyl, etc. Examples of such aldehydes include, but arenot limited to, formaldehyde, acetaldehyde, propionaldehyde,butyraldehyde, iso-butyraldehyde, n-valeraldehyde, benzaldehyde,crotonaldehyde, cinnamaldehyde, glyoxal, glutaraldehyde, furfural,phenylacetaldehyde, chloral, chloroacetaldehyde, dichloroacetaldehydelaurylaldehyde, palmitylaldehyde, stearylaldehyde, and mixtures thereof.In addition to formaldehyde, paraformaldehyde, trioxane and tetraoxanecan also be used. While aldehyde is preferred, ketone can be usedinstead. An example of suitable ketones is acetone.

[0032] The phenolic novolak resin can be effectively synthesized in thepresence of an acid, base or ortho-directing catalyst, although it isnot always necessary. Examples of suitable acid catalysts include, butare not limited to, those acids such as sulfuric, hydrochloric,phosphoric, methanesulfonic, trifluoromethanesulfonic, trifluoroacetic,formic, oxalic, benzenesulfonic, p-toluenesulfonic, mixtures thereof andthe like. Examples of suitable base catalysts include, but are notlimited to, alkali or alkaline earth metal hydroxides and carbonates.Catalysts suitable for use in the synthesis of an ortho substitutedphenolic novolak resin can be weak organic acid salts of a divalentmetal ion such as calcium, magnesium, zinc, strontium, cadmium, leadand/or barium.

[0033] The phenolic novolak resins suitable for synthesis of silanemodified resins include, but are not limited to, phenol-formaldehydenovolak, phenol-alkylphenol-formaldehyde novolak,phenol-aralkylphenol-formaldehyde novolak, high orthophenol-formaldehyde novolak, phenol-resorcinol-formaldehyde novolak,alkylphenol-resorcinol-formaldehyde novolak,aralkylphenol-resorcinol-formaldehyde novolak, resorcinol-formaldehydenovolak, alkylresorcinol-formaldehyde novolak,alkylresorcinol-resorcinol-formaldehyde novolak,aralkylresorcinol-resorcinol-formaldehyde novolak, and mixtures thereof.

[0034] In some embodiments, modified phenolic resins are used as thestarting material in making the silane modified resins. The modifiedphenolic resins are obtained by reacting a phenolic compound, analdehyde or ketone, and an olefinically unsaturated compound,simultaneously or sequentially. Suitable olefinically unsaturatedcompounds include, but are not limited to, vinyl aromatics generallyrepresented by the following formula: R′—CH═CH₂, wherein R′ is phenyl,substituted phenyl, or other aromatic group. Examples of suitableolefinically unsaturated compounds include, but are not limited to,styrene, α-methylstyrene, p-methylstyrene, α-chlorostyrene,divinylbenzene, vinyl-naphthalene, indene, and vinyl toluene. In somereactions, styrene is used as the olefinically unsaturated compound, andthe resulting resin is a styrenated phenolic resin. Typically, the molarratio of the phenolic compound to the olefinically unsaturated compoundis between about 1:0.4 to about 1:1. In some embodiments, the molarratio is from about 1:0.5 to about 1:0.9, from about 1:0.55 to about1:0.8, from about 1:0.6 to 1:0.7. In other embodiments, the molar ratiois between about 1:0.60 and about 1:0.65. Additional reaction conditionsare disclosed in U.S. Pat. No. 5,021,522 and U.S. Pat. No. 5,049,641,which are incorporated by reference herein in their entirety.

[0035] As described above, silane modified phenolic novolak resins canbe prepared by the reaction of a phenolic resin or a blend with one ormore silanes having the chemical structure represented by Formula (C),(D) or (E) under neutral conditions:

[0036] wherein R₆, R₇ and R₈ are independently an alkyl group of 1 to 4carbon atoms, an alkoxy group of 1 to 8 carbon atoms, phenyl group, or acycloalkyl group; R₉ is a divalent saturated or unsaturated aliphaticstraight or branched hydrocarbon group with 1 to 12 carbon atoms; X is athiol (—SH), isocyanato (—NCO), urea (—NH—(C═O)—NH₂) or glycidylether(epoxy) group; Z is an S_(x) (x=1-8) or NH group; and R₁₀ is a vinyl(—CH═CH₂) group or an alkoxy group.

[0037] Examples of suitable silanes according to Formula C include, butare not limited to, 3-(aminopropyl)triethoxysilane,3-(isocyanatopropyl)triethoxysilane,3-(glycidyloxypropyl)trimethoxysilane,3-(mercaptopropyl)trimethoxysilane,N-beta-aminoethyl-3(aminopropyl)trimethoxysilane,3-(aminopropyl)trimethoxysilane, 3-(aminoethyl)triethoxysilane,3-(glycidyloxyethyl)triethoxysilane, 3-(mercaptopropyl)triethoxysilane,N-beta-aminoethyl-3-(aminoethyl)trimethoxysilane,3-(aminobutyl)triethoxysilane, 3-(aminoethyl)trimethoxysilane,3-(aminopropyl)methyldiethoxysilane, N-(3-(triethoxysilyl)propyl)ureaand the like.

[0038] Examples of suitable silanes according to Formula D include, butare not limited to, bis-silyl polysulfur silanes including3,3′-bis(trimethoxysilylpropyl)disulfide,3,3′-bis(triethoxysilylpropyl)tetrasulfide,3,3′-bis(trimethoxysilylpropyl)tetrasulfide,2,2′-bis(triethoxysilylethyl)tetrasulfide,3,3′-bis(trimethoxysilylpropyl)trisulfide,3,3′-bis(triethoxysilylpropyl)trisulfide,3,3′-bis(trimethoxysilylpropyl)hexasulfide,3,3′-bis(trimethoxysilylpropyl)octasulfide,3,3′-bis(trioctoxysilylpropyl)tetrasulfide,3,3′-bis(trihexoxysilylpropyl)disulfide, bis-silylaminosilanes, and soon.

[0039] Examples of suitable silanes according to Formula E include, butare not limited to, vinylmethyldiethoxysilane,vinylmethyldimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane,vinyltriisopropoxysilane, vinyltriisopropenoxysilane,vinyltrimethoxysilane, vinyltriphenoxysilane,vinyltris(2-methoxyethoxy)silane, vinyldimethylethoxysilane, and thelike.

[0040] The silane-modified phenolic resin is prepared, for example, bymixing a phenolic resin and a silane, heating the mixture to removealcohol formed by dealcoholization condensation reaction. The reactiontemperature is about 70° C. to about 150° C., preferably about 80° C. toabout 110° C. The total reaction time may vary from about 0.5 hour toabout 15 hours. This reaction is preferably performed undersubstantially anhydrous conditions to prevent the condensation reactionof the silane itself. Additional reaction conditions suitable forcarrying out the reactions are disclosed in U.S. Pat. No. 4,022,753;U.S. Pat. No. 5,177,157; U.S. Pat. No. 5,736,619; and U.S. Pat. No.6,441,106, which are incorporated by reference herein in their entirety.

[0041] In the dealcoholization reaction, catalysts may be used toaccelerate the reaction. Examples of the catalyst include, but are notlimited to, acetic acid, p-toluenesulfonic acid, benzoic acid, propionicacid and like organic acids; lithium, sodium, potassium, rubidium,cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium,cobalt, germanium, tin, lead, antimony, arsenic, cerium, boron, cadmium,manganese and like metals; oxides, organic acid salts, halides,alkoxides and the like of these metals. Among these, organic acids,organotin, tin organoate are particularly preferable. More specifically,acetic acid, dibutyltin dilaurate, tin octoate, etc., are alsopreferred.

[0042] The above reaction can be performed in a solvent or without asolvent. The solvent is not particularly limited insofar as it candissolve the phenolic resin and silane. Examples of such solvent includedimethylformamide, dimethylacetamide, methyl ethyl ketone andcyclohexanone. If the rapid progress of dealcoholization reaction isdesired, the reaction is preferably performed without the solvent.However, it is favorable to use a solvent when the viscosity of thereaction system is excessively increased.

[0043] In the above reaction, in order to obtain the silane-modifiedphenolic resin having the desired phenolic hydroxyl equivalent andviscosity, the dealcoholization reaction between the phenolic resin andsilane may be stopped in the course of the reaction. A number of methodscan be used to stop the reaction. For example, effective methods arecooling, deactivating the catalyst or adding alcohol to the reactionsystem upon obtaining the desired amount of alcohol effluent.

[0044] The thus-obtained silane-modified phenolic resin contains, as amain component, the phenolic resin having at least one of the phenolichydroxyl groups being modified with silane. The resin may containunreacted phenolic resin and silane, which can be separated, if desired.

[0045] In the preparation of a silane modified phenolic novolak resin,the weight ratio of silane to novolak resin can vary between 1:99 to99:1. Due to the high cost of silanes, a silane is used at a silane tonovolak resin weight ratio from about 0.5:100 to about 20:100 or fromabout 0.5:100 to about 5:100. In some embodiments, the ratio of theequivalent number of alkoxy groups in a silane to the equivalent numberof phenolic hydroxyl groups in a phenolic novolak resin is less than 1,preferably less than about 0.5, less than about 0.01, less than about0.009, less than about 0.008; less than about 0.007, less than about0.006, less than about 0.005, or less than about 0.0001.

[0046] As mentioned above, a vulcanizable rubber composition can beprepared by using the silane-modified phenolic resin as the methyleneacceptor. The vulcanizable rubber composition comprises: (I) a rubbercomponent (which can be natural or synthetic rubber); and (II) amethylene donor compound which generates formaldehyde by heating; and(III) a methylene acceptor which is based on the silane-modifiedphenolic resin described herein. Optionally, the rubber composition mayfurther comprise (IV) a vulcanizing agent, such as sulfur; and (V) oneor more rubber additives. In some embodiments, the vulcanizable rubbercomposition is formulated using a methylene acceptor based on a phenolicresin not modified by a silane. Such phenolic resins are described inthe above. For example, one such resin is phenol/t-octylphenol/formaldehyde novolak.

[0047] The rubber component can be any natural rubber, synthetic rubberor combination thereof. Specific examples of synthetic rubbers includeneoprene (polychloroprene), polybutadiene, polyisoprene, butyl rubber,copolymers of 1,3-butadiene or isoprene with monomers such as styrene,acrylonitrile and methyl methacrylate as well asethylene/propylene/diene monomer (EPD M) and in particularethylene/propylene/dicyclopentadiene terpolymers.

[0048] The methylene donor component can be any compound that generatesformaldehyde upon heating during the vulcanization and capable ofreacting with the methylene acceptor used in the rubber compoundformulations. Examples of suitable methylene donors include, but are notlimited to, hexamethylenetetramine (HEXA or HMT) andhexamethoxymethylmelamine (HMMM). Other suitable methylene donors aredescribed in U.S. Pat. No. 3,751,331, which is incorporated by referenceherein in its entirety. The methylene donor is usually present inconcentrations from about 0.5 to 15 parts per one hundred parts ofrubber, preferably from 0.5 to 10 parts per one hundred parts of rubber.The weight ratio of methylene donor to methylene acceptor may vary. But,in general, the weight-ratio will range from 1:10 to 10:1. Preferably,the weight ratio of methylene donor to methylene acceptor ranges from1:3 to 3:1.

[0049] The vulcanizable rubber composition may include a vulcanizingagent, such as sulfur. Examples of suitable sulfur vulcanizing agentsinclude elemental sulfur or sulfur donating vulcanizing agents.Preferably, the sulfur vulcanizing agent is elemental sulfur. Othercross-linking agents may also be used.

[0050] The vulcanizable rubber composition may also include one or moreof additives used in rubber compositions. The additives commonly used inthe rubber stocks include carbon black, cobalt salts, stearic acid,silica, zinc oxide, fillers, plasticizers, waxes, processing oils,retarders, antiozonants and the like.

[0051] Accelerators are also used to control the time and/or temperaturerequired for the vulcanization and to improve the properties of thevulcanizate. Suitable accelerators include, but are not limited to,amines, disulfides, guanidines, thioureas, thiazoles, thiurams,sulfenamides, dithicarbonates and zanthates. Preferably, the primaryaccelerator is a sulfenamide.

[0052] Embodiments of the invention also provide a method for improvingthe adhesion of rubber to reinforcing materials, thus a method of makinga fabricated rubber article due to the improved adhesion between rubberand a reinforcing material. The method comprises (i) mixing across-linking agent with a vulcanizable rubber composition made inaccordance with an embodiment of the invention as described above; (ii)embedding a reinforcing material in the vulcanizable rubber compositionbefore the rubber composition is cross-linked; and (iii) effectingcross-linking of the rubber composition. Preferably, the reinforcingmaterial is not coated with a silane composition before the embedding.In other words, the reinforcing material is substantially free of asilane coating before the embedding. The term “embedding” means that thereinforcing material is combined with a rubber composition in anysuitable manner, such as laminating, calendering, mixing, etc. While itis preferred to have the reinforcing material closely enclosed in amatrix of the rubber composition, it need not be the case. While thesilane-modified phenolic resin is not substantially cross-linked beforeit is used in a rubber composition, it should be understood that itbecomes cross-linked when the rubber composition is vulcanized.

[0053] The reinforcing material can be in the form of cords, wires,fibers, filaments, fabrics, etc. Examples of suitable reinforcingmaterials include, but are not limited to steel (which can be coated bybrass, zinc or bronze), polyester, nylon, aramid, fiberglass, and otherorganic or inorganic compositions.

[0054] While not necessary, the reinforcing material can be coated withan adhesive composition before it is combined with a uncured rubbercomposition. Any adhesive composition that enhances the adhesion betweenthe reinforcing material and the cured rubber component can be used. Forexamples, certain suitable adhesive compositions for enhancing theadhesion between rubber and a reinforcing material are disclosed in thefollowing U.S. Pat. Nos. 6,416,869; 6,261,638; 5,789,080; 5,126,501;4,588,645; 4,441,946; 4,236,564; 4,051,281; 4,052,524; and 4,333,787,which are incorporated by reference herein in their entirety. Theseadhesive compositions can be used according to the methods taughttherein, with or without modifications. However, the adhesivecomposition for coating the reinforcing material does not include thesilanes represented by Formulas (C), (D), and (E).

[0055] The rubber compositions based on the above resins may be used inthe manufacture of composite products, such as tires, power belts,conveyor belts, printing rolls, rubber shoe heels and soles, rubberwringers, automobile floor mats, mud flaps for trucks, ball mill liners,and the like. The rubber compositions described herein also may be usedas a wire coat or bead coat for use in tire applications. Any form ofcobalt compounds known in to promote the adhesion of rubber to metal,such as stainless steel, may be used. Suitable cobalt compounds include,but are not limited to, cobalt salts of fatty acids, such as stearicacid, palmitic, oleic, linoleic and the like; cobalt salts of aliphaticor alicyclic carbocylic acids having 6 to 30 carbon atoms; cobaltchloride, cobalt naphthenate, cobalt neodeconoate, and anorgano-cobalt-boron complex commercially available under the trade nameManobond® 680C from OM Group, Inc., Cleveland, Ohio.

[0056] The following examples are presented to exemplify embodiments ofthe invention. All numerical values are approximate. When numericalranges are given, it should be understood that embodiments outside thestated ranges may still fall within the scope of the invention. Specificdetails described in each example should not be construed as necessaryfeatures of the invention.

[0057] Cure properties were measured with an Alpha Technologies MDRRheometer at 150° C., 0.5° arc and 1.67 Hz according to ASTM D-5289.Wire pullout adhesion was determined for each test compound by ASTMD-2229-02 using brass plated steel cord with 63.7% copper platingembedded 19 mm into the rubber pad.

[0058] The softening point of the resins was measured according to thefollowing method with reference to the latest edition of ASTM E 28 andASTM D 3104, which are incorporated by reference herein in theirentirety.

[0059] Apparatus: cups—pitch type drilled to 0.257″ opening (F drill); a440 stainless steel ball (0.2500″ in diameter and must pass throughcups); a Mettler softening point apparatus comprising (1) a control unitModel FP-90 or equivalent, (2) a furnace Model FP-83 or equivalent, and(3) cartridge assemblies; a timer; porcelain evaporating dishes (about3″ in diameter); and a hot plate. For calibration of the Mettlerapparatus, see ASTM D 3104, which is incorporated by reference herein.

[0060] Procedures:

[0061] Melt 15 grams of resin in a porcelain or aluminum evaporatingdish. At 600-650° F., surface temperature of hot plate, melting time isapproximately 4 minutes. Overheating should be avoided. When the resinis melted, pour into cups that have been preheated to at least thetemperature of the molten resin. The quantity of resin poured into thecups should be such that after solidification the excess can be removedwith a heated spatula or putty knife. An aluminum plate with holesdrilled in it to form a support on the sides and bottom of the cup canbe used, or they can be held with forceps when removing excess resin.After the samples have been cooled to room temperature in a desiccator,assemble the cartridge so that the ball rests on the top of the resin.Place the assembled cartridge in the furnace, which has been preset to85° C. or 10-15° C. below the expected soft point. Set the heating rateat 1° C./min. Turn the cartridge until it locks into position, and wait30 seconds. Then, initiate operation of softening point apparatus. Readthe completed softening point on the indicator. Duplicate determinationsshould not differ by more than 1.0° C.

EXAMPLE 1 Synthesis of Resorcinol-Formaldehyde Novolak Resin Modifiedwith 3-(Aminopropyl)triethoxysilane

[0062] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condenser, and an addition funnel, 143.1 grams (1.3mole) of resorcinol was charged and heated to 120-130° C. After reachingthe temperature, 63.4 grams (0.79) moles of 37.6% formaldehyde was addeddropwise over a period of 90-120 minutes under reflux conditions. Uponcompletion of the formaldehyde addition, the reaction was allowed toreflux for an additional 30-60 minutes. The reaction temperature wasincreased to remove water distillate under atmospheric pressure and thenunder reduced pressure. Once distillation was complete, the reactiontemperature was adjusted to 120-140° C. 3-(Aminopropyl)triethoxysilane,at a level of about 3 wt. % of the resin yield, was added dropwise andallowed to mix for 15-30 minutes. The final product had a softeningpoint of 107.7° C. with a free resorcinol content of 17 weight percentby Gas Chromatography/Liquid Chromatography (“GC/LC”) analysis.Carbon-13 and proton NMR analysis revealed chemical shiftscharacteristic of a mixture of resorcinol/formaldehyde resin and freeresorcinol. NMR spectral evidence does indicate that the amino group hasreacted with the resorcinolic hydroxyls to form aryl-NH—CH₂ CH₂ CH₂—Sistructures. No unreacted —CH₂NH₂ structure was observed.

EXAMPLE 2 Synthesis of Resorcinol-Formaldehyde Novolak Resin Modifiedwith Triethoxyvinylsilane

[0063] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, and an addition funnel, 143.1 grams (1.3mole) of resorcinol was charged and heated to 120-130° C. After reachingthe temperature, 63.4 grams (0.79 moles) of 37.6% formaldehyde was addeddropwise over a period of 90-120 minutes under reflux conditions. Uponcompletion of the formaldehyde addition, the reaction was allowed toreflux for an additional 30-60 minutes. After cooling to 95-105° C., 1.7grams of oxalic acid was charged to the reaction and held under refluxconditions for 15-30 minutes. The reaction temperature was increased toremove water distillate under atmospheric pressure and then underreduced pressure. Once distillation was complete, the reactiontemperature was adjusted to 120-140° C. Triethoxyvinylsilane, at a levelof about 3 wt. % of the resin yield, was added dropwise and allowed tomix for 15-30 minutes. The final product had a softening point of 105.4°C. with a free resorcinol content of 17 weight percent determined byGC/LC analysis. Carbon-13 and proton NMR analysis revealed chemicalshifts characteristic of a mixture of resorcinol/formaldehyde resin andfree resorcinol. In addition, no ethoxysilane structure (Si—O—CH₂CH₃) orunreacted vinyl structure were detected.

EXAMPLE 3 Synthesis of Phenolic and Resorcinolic Novolak Resin BlendModified with Triethoxy(3-isocyanatopropyl)silane

[0064] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, Dean Stark, and an addition funnel, 128.3grams (1.35 mole) of phenol, 21.3 grams (0.1 mole) t-octylphenol, 1.0gram p-toluene sulfonic acid, and 50-70 grams of toluene were chargedand heated to reflux. After reaching the refluxing temperature, 83.9grams (1.05) moles of 37.6% formaldehyde was added dropwise over aperiod of 3-5 hours under reflux conditions. Water from the formaldehydesolution was collected and drained from the Dean Stark during theaddition. Upon completion of the formaldehyde addition, the reaction wasallowed to reflux for an additional 30-60 minutes. After cooling to90-95° C., 0.5 grams of 50% sodium hydroxide was charged to neutralizethe acid catalyst. The reaction temperature was increased to 110-120°C., then 165.0 grams of Penacolite® R-50, a resorcinol/formaldehyderesin, was added dropwise over 20-60 minutes under reflux conditions.The reaction temperature was increased to remove water distillate underatmospheric pressure and then under reduced pressure. Once distillationwas complete, the reaction temperature was adjusted to 120-140° C.Triethoxy(3-isocyanatopropyl)silane, at a level of about 3 wt. % of theresin yield, was added dropwise and allowed to mix for 15-30 minutes.The final product had a softening point of 105.0° C. GC/LC analysisshowed a free phenol content of 1.5 weight percent, a free t-octylphenolcontent of 1.7 weight percent, and a free resorcinol content of 6.0weight percent.

[0065] IR analysis revealed absorption peaks characteristic of aphenol/resorcinol/formaldehyde resin containing low level carbamatestructures [—O—C(═O)—NH—] from the reaction of the isocyanate structurewith a hydroxyl group. Little, if any, unreacted —N═C═O structure wasdetected.

EXAMPLE 4 Synthesis of t-Octylphenol-Formaldehyde-Resorcinol NovolakResin Modified with Bis(3-(trimethoxysilyl)propyl)amine

[0066] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, and an addition funnel, 106.3 grams (0.50mole) of t-octylphenol, 25.3 grams (0.80 mole) of paraformaldehyde (95%,untreated), 19.2 grams (0.24 mole) of 37.6% formaldehyde, and 43.2 gramsof xylene was charged and heated to 75-80° C. After reaching thetemperature, 6.4 grams (0.04 moles) of 25% sodium hydroxide was addeddropwise over a period of 20-30 minutes. The reaction was heated to85-90° C. and held for 3-5 hours. The reaction was cooled to 60-65° C.and resorcinol was charged over 15-20 minutes. After the resorcinolcharge, the reaction was heated to 100-110° C. and held for 60-90minutes. After cooling the reaction to 85-90° C., 7.8 grams (0.04 moles)of 50% sulfuric acid was slowly added over 5-10 minutes. The reactiontemperature was increased to remove water distillate under atmosphericpressure and then under reduced pressure. Once distillation wascomplete, the reaction temperature was adjusted to 120-140° C.Bis(3-(trimethoxysilyl)propyl)amine (BTPA), at a level of about 3 wt. %of the resin yield, was added dropwise and allowed to mix for 15-30minutes. The final product had a softening point of 116.5° C. GC/LCanalysis showed a free resorcinol content of 8.6 weight percent, a freephenol content of 0.14 weight percent, and a free t-octylphenol contentof 2.7 weight percent.

EXAMPLE 5 Synthesis of Resorcinol-Formaldehyde Novolak Resin Modifiedwith Tris(2-methoxyethoxy)vinylsilane

[0067] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, and an addition funnel, 143.1 grams (1.3mole) of resorcinol was charged and heated to 120-130° C. After reachingthe temperature, 63.4 grams (0.79) moles of 37.6% formaldehyde was addeddropwise over a period of 90-120 minutes under reflux conditions. Uponcompletion of the formaldehyde addition, the reaction was allowed toreflux for an additional 30-60 minutes. After cooling to 95-105° C., 1.7grams of oxalic acid was charged to the reaction and held under refluxconditions for 15-30 minutes. The reaction temperature was increased toremove water distillate under atmospheric pressure and then underreduced pressure. Once distillation was complete, the reactiontemperature was adjusted to 120-140° C.Tris(2-methoxyethoxy)vinylsilane, at a level of about 3 wt. % of theresin yield, was added dropwise and allowed to mix for 15-30 minutes.The final product had a softening point of 106.6° C. with a freeresorcinol content of 17 weight percent by GC/LC analysis. Carbon-13 andproton NMR analysis revealed chemical shifts characteristic of a mixtureof resorcinol/formaldehyde resin and free resorcinol. Also, no2-methoxyethoxysilane or unreacted vinyl structures were detected. Theabsence of methoxyethoxysilane structure (Si—OCH₂CH₂OCH₃) indicateshydrolysis to SiOH groups by a possible reaction with the hydroxylgroups present in the resorcinolic resin.

EXAMPLE 6 Synthesis of Resorcinol-Styrene-Formaldehyde Novolak ResinModified with Trimethoxyvinylsilane

[0068] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, and an addition funnel, 110.1 grams (1.0mole) of resorcinol and 0.35 grams of p-toluene sulfonic acid werecharged and heated to 120-130° C. After reaching the temperature, 73.6grams (0.70 mole) of styrene was added dropwise over 30-60 minutes at125-130° C. After the styrene charge, the reaction was held at 125-135°C. for 15-30 minutes. The temperature was then increased to 150-155° C.and maintained for 15-30 minutes. After cooling to 130-140° C., 6.0grams (0.055 mole) of additional resorcinol was slowly added. Once thesecond resorcinol charge was added, 51.8 grams (0.65) moles of 37.7%formaldehyde was added dropwise over a period of 30-60 minutes underreflux conditions. Upon completion of the formaldehyde addition, thereaction was cooled to 90-100° C. After cooling to 90-100° C., 3.6 gramsof denatured alcohol was charged to the reaction. Then 0.2 grams of 50%sodium hydroxide was added to neutralize the catalyst. The reactiontemperature was increased to remove water distillate under atmosphericpressure and then under reduced pressure. Once distillation wascomplete, the reaction temperature was adjusted to 120-140° C.Trimethoxyvinylsilane, at a level of about 3 wt. % of the resin yield,was added dropwise and allowed to mix for 15-30 minutes. The finalproduct had a softening point of 104.3° C. with a free resorcinolcontent of 0.83 weight percent. Proton NMR analysis revealed the absenceof unreacted vinyl silane in the resin and also indicated the presenceof aryl-CH(CH₃)—Si and Si—O—CH₃ groups in the modified resin. Thepresence of aryl-CH(CH₃)—Si group indicated the reaction of vinyl silanewith the resorcinol or resorcinolic resin present in the resin product.

EXAMPLE 7 Synthesis of Resorcinol-Styrene-Formaldehyde Novolak ResinModified with (N-(3-triethoxysilyl)propyl)urea

[0069] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condenser, and an addition funnel, 110.1 grams (1.0mole) of resorcinol and 0.35 grams of p-toluene sulfonic acid werecharged and heated to 120-130° C. After reaching the temperature, 73.6grams (0.70 mole) of styrene was added dropwise over 30-60 minutes at125-130° C. After the styrene charge, the reaction was held at 125-135°C. for 15-30 minutes. The temperature was then increased to 150-155° C.and maintained for 15-30 minutes. After cooling to 130-140° C., 6.0grams (0.055 mole) of additional resorcinol was slowly added. Once thesecond resorcinol charge was added, 51.8 grams (0.65) moles of 37.7%formaldehyde was added dropwise over a period of 30-60 minutes underreflux conditions. Upon completion of the formaldehyde addition, thereaction was cooled to 90-100° C. After cooling to 90-100° C., 3.6 gramsof denatured alcohol was charged to the reaction. Then 0.2 grams of 50%sodium hydroxide was added to neutralize the catalyst. The reactiontemperature was increased to remove water distillate under atmosphericpressure and then under reduced pressure. Once distillation wascomplete, the reaction temperature was adjusted to 120-140° C.N-(3-triethoxysilyl)propyl)urea solution (50% in methanol), at a levelof about 3 wt. % of the resin yield, was added dropwise and allowed tomix for 15-30 minutes. The final product had a softening point of 98.2°C. with a free resorcinol content of 0.77 weight percent. The proton NMRanalysis indicated the presence of aryl-NH—C(═O)—NHCH₂— and Si—O—CH₂CH₃groups in the resin structure, suggesting the reaction of the addedsilane with the resorcinol or resorcinolic resin.

EXAMPLE 8 Synthesis of Resorcinol-Styrene-Formaldehyde Novolak ResinModified with 3-(Aminopropyl)triethoxysilane

[0070] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condenser, and an addition funnel, 110.1 grams (1.0mole) of resorcinol and 0.35 grams of p-toluene sulfonic acid werecharged and heated to 120-130° C. After reaching the temperature, 73.6grams (0.70 mole) of styrene was added dropwise over 30-60 minutes at125-130° C. After the styrene charge, the reaction was held at 125-135°C. for 15-30 minutes. The temperature was then increased to 150-155° C.and maintained for 15-30 minutes. After cooling to 130-140° C., 6.0grams (0.055 mole) of additional resorcinol was slowly added. Once thesecond resorcinol charge was added, 51.8 grams (0.65) moles of 37.7%formaldehyde was added dropwise over a period of 30-60 minutes underreflux conditions. Upon completion of the formaldehyde addition, thereaction was cooled to 90-100° C. After cooling to 90-100° C., 3.6 gramsof denatured alcohol was charged to the reaction. Then 0.2 grams of 50%sodium hydroxide was added to neutralize the catalyst. The reactiontemperature was increased to remove water distillate under atmosphericpressure and then under reduced pressure. Once distillation wascomplete, the reaction temperature was adjusted to 120-140° C.3-(Aminopropyl)triethoxysilane, at a level of about 3 wt. % of the resinyield, was added dropwise and allowed to mix for 15-30 minutes. Thefinal product had a softening point of 110.4° C. with a free resorcinolcontent of 0.76 weight percent. Proton NMR analysis revealed thepresence of aryl-N(H)—CH₂CH₂CH₂—Si and Si—O—CH₂CH₃ groups and theabsence of unreacted Si—CH₂CH₂CH₂—NH₂ group. The presence ofaryl-N(H)—CH₂CH₂CH₂—Si group in the resin structure indicated a reactionof the added silane with the resorcinol or resorcinolic resin.

EXAMPLE 9 Synthesis of Resorcinol-Styrene-Formaldehyde Novolak ResinModified with (3-mercaptopropyl)triethoxysilane

[0071] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, and an addition funnel, 110.1 grams (1.0mole) of resorcinol and 0.35 grams of p-toluene sulfonic acid werecharged and heated to 120-130° C. After reaching the temperature, 73.6grams (0.70 mole) of styrene was added dropwise over 30-60 minutes at125-130° C. After the styrene charge, the reaction was held at 125-135°C. for 15-30 minutes. The temperature was then increased to 150-155° C.and maintained for 15-30 minutes. After cooling to 130-140° C., 6.0grams (0.055 mole) of additional resorcinol was slowly added. Once thesecond resorcinol charge was added, 51.8 grams (0.65) moles of 37.7%formaldehyde was added dropwise over a period of 30-60 minutes underreflux conditions. Upon completion of the formaldehyde addition, thereaction was cooled to 90-100° C. After cooling to 90-100° C., 3.6 gramsof denatured alcohol was charged to the reaction. Then 0.2 grams of 50%sodium hydroxide was added to neutralize the catalyst. The reactiontemperature was increased to remove water distillate under atmosphericpressure and then under reduced pressure. Once distillation wascomplete, the reaction temperature was adjusted to 120-140° C.(3-Mercaptopropyl)triethoxysilane, at a level of about 3 wt. % of theresin yield, was added dropwise and allowed to mix for 15-30 minutes.The final silane modified product had a softening point of 110.4° C.with a free resorcinol content of 0.82 weight percent.

EXAMPLE 10 Synthesis of Phenol-Formaldehyde Novolak Resin Modified with3-(isocyanatopropyl)triethoxysilane

[0072] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, and an addition funnel, 137.8 grams (1.45mole) of phenol and 1.0 gram of p-toluene sulfonic acid were charged andheated to 90-95° C. After reaching the temperature, 83.9 grams (1.05)moles of 37.6% formaldehyde was added dropwise over a period of 60-120minutes at 95-100° C. Upon completion of the formaldehyde addition, thereaction was heated to reflux. The reaction was held for 2-4 hours underreflux conditions. After reflux, 0.5 grams of 50% sodium hydroxide wasadded to neutralize the acid catalyst. The reaction temperature wasincreased to remove water distillate under atmospheric pressure and thenunder reduced pressure. Once distillation was complete, the reactiontemperature was adjusted to 120-140° C.Triethoxy(3-isocyanatopropyl)silane, at a level of about 3 wt. % of theresin yield, was added dropwise and allowed to mix for 15-30 minutes.The final silane modified product had a softening point of 96.5° C. anda free phenol content of 2.6 weight percent by GC/LC analysis. IRanalysis revealed absorptions characteristic of a phenol/formaldehyderesin containing a low level of carbamate structure [—O—C(═O)—N(—H)—].The carbamate structure is the result of the reaction of —N═C═Ostructure with an aryl-OH group. Little, if any, unreacted —N═C═Ostructure was detected. Proton NMR analysis indicated the presence ofaryl-O—C(═O)NH—CH₂CH₂CH₂—Si— and Si—OCH₂CH₃ groups, confirming thereaction of the silane and the phenolic resin.

EXAMPLE 11 Synthesis of Phenol-t-Octylphenol-Formaldehyde Novolak ResinModified with (3-mercaptopropyl)triethoxysilane

[0073] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condensor, and an addition funnel, 128.3 grams (1.35mole) of phenol, 21.3 grams (0.1 mole) of t-octylphenol, and 1.0 gram ofp-toluene sulfonic acid were charged and heated to 90-95° C. Afterreaching the temperature, 83.9 grams (1.05) moles of 37.6% formaldehydewas added dropwise over a period of 60-120 minutes at 95-100° C. Uponcompletion of the formaldehyde addition, the reaction was heated toreflux. The reaction was held for 2-4 hours under reflux conditions.After reflux, 0.5 grams of 50% sodium hydroxide was added to neutralizethe acid catalyst. The reaction temperature was increased to removewater distillate under atmospheric pressure and then under reducedpressure. Once distillation was complete, the reaction temperature wasadjusted to 120-140° C. (3-Mercaptopropyl)-triethoxysilane, at a levelof about 3 wt. % of the resin yield, was added dropwise and allowed tomix for 15-30 minutes. The final silane modified resin product had asoftening point of 93.7° C. with a free phenol content of 0.98 weightpercent and a free t-octylphenol content of 3.7 weight percent by GC/LCanalysis.

EXAMPLE 12 Synthesis of Phenolic Novolak Resin Modified withTriethoxyvinylsilane

[0074] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condenser, and an addition funnel, 128.3 grams (1.35mole) of phenol, 21.3 grams (0.1 mole) of t-octyl phenol, and 1.0 gramsof zinc acetate were charged and heated to 45-55° C. After reaching thetemperature, 59.9 grams (0.75 mole) of 37.6% formaldehyde was addedstreamwise over 5-10 minutes. After the formaldehyde charge, thereaction was heated to reflux and maintained for 1-2 hours. The reactionwas cooled to 85-95° C. and another 24.0 grams (0.3 moles) of 37.6%formaldehyde was added dropwise over 15-30 minutes at 85-95° C. Afterthe addition, the reaction was heated to reflux and maintained foranother 1-2 hours. The reaction temperature was then increased to removewater distillate under atmospheric pressure. The distillate wascollected to 125-130° C. Once the first distillation was complete, thereaction was again set-up for reflux. The reaction was held under refluxfor an additional 1-2 hours. The reaction temperature was increased toremove water distillate under atmospheric pressure for the second time.The distillate was collected to 150-155° C., then distilled under vacuumconditions to 155-160° C. Once distillation was complete, the reactiontemperature was adjusted to 120-140° C. Triethoxyvinylsilane, at a levelof about 3 wt. % of the resin yield, was added dropwise and allowed tomix for 15-30 minutes. The final product had a softening point of 100.9°C. with a free phenol content of 2.0 weight percent, a free t-octylphenol content of 1.4 weight percent, and a free triethoxyvinylsilanecontent of 1.2 weight percent by GC/LC analysis.

EXAMPLE 13 Synthesis of Phenolic Novolak Resin Without SilaneModification

[0075] Into a 500 mL reaction kettle equipped with a stirrer,thermometer, reflux condenser, and an addition funnel, 128.3 grams (1.35mole) of phenol, 21.3 grams (0.1 mole) of t-octyl phenol, and 1.0 gramsof zinc acetate were charged and heated to 45-55° C. After reaching thetemperature, 59.9 grams (0.75 mole) of 37.6% formaldehyde was addedstreamwise over 5-10 minutes. After the formaldehyde charge, thereaction was heated to reflux and maintained for 1-2 hours. The reactionwas cooled to 85-95° C. and another 24.0 grams (0.3 moles) of 37.6%formaldehyde was added dropwise over 15-30 minutes at 85-95° C. Afterthe addition, the reaction was heated to reflux and maintained foranother 1-2 hours. The reaction temperature was then increased to removewater distillate under atmospheric pressure. The distillate wascollected to 125-130° C. Once the first distillation was complete, thereaction was again set-up for reflux. The reaction was held under refluxfor an additional 1-2 hours. The reaction temperature was increased toremove water distillate under atmospheric pressure for the second time.The distillate was collected to 150-155° C., then distilled under vacuumconditions to 155-160° C. The resin obtained from the reactor had asoftening point of 108.7° C. with a free phenol content of 2.6 weightpercent and a t-octyl phenol of 1.3 weight percent by GC/LC analysis.

EXAMPLE 14 Rubber Compounding and Testing

[0076] The methylene acceptor resins prepared according to examples 12and 13 were evaluated in a black natural rubber compound to assess theirperformance for the improved steel-wire adhesion properties under heatand humidity aged conditions. Black natural rubber compositions, havingthe formulation shown in Table 1, were prepared in a 3-stage mixingprocedure. These rubber compositions were then used to evaluate theadhesion effects of the compounds as methylene acceptors in combinationwith the methylene donor hexamethoxymethylmelamine (HMMM). The methylenedonor/acceptor ratio was kept at 2:3 for the methylene acceptor with acombined loading of 5 parts by weight in the rubber compound. TABLE 1Rubber Composition Formulation Rubber Compound Used in Testing Parts byMaster Batch Weight First Stage  1. Natural Rubber 100  2. Carbon Black55  3. Zinc Oxide 8  4. Stearic Acid 1  5.N-(1,2-Dimethylbutyl)-N′-Phenyl-p-Phenylene Diamine 2  6.Pre-Vulcanization Inhibitor [N-(Cyclohexylthio) 0.2     Phthalimide]  7.Polymerized 1,2-Dihydro-2,2,4-Trimethyl Quinoline 1 Second Stage  8.Methylene Acceptor (Phenolic/Resorcinolic Resin) 3  9. Cobalt Salt(Manobond 680 C., 22% Co) 0.45 Third Stage (Final) 10. Insoluble Sulfur(80%, oiled) 5 11. N.N-Dicylohexyl-2-Benzenethiazole Sulfenamide 1 12.Methylene Donor (HMMM, 72% Active) 2.78

[0077] The rubber masterbatch was mixed in the first stage to about 150°C. temperature in a Banbury mixer. In a second stage, a methyleneacceptor and a cobalt salt were mixed into an appropriate amount ofmasterbatch on to the two roll mill at about 121° C. Insoluble sulfur,an accelerator, and an appropriate amount of HMMM as indicated in Table1 were mixed in the third stage at 95° C. The test compounds wereconditioned overnight in a constant temperature room at about 23° C. and50% relative humidity. The compounds were then tested for Rheometercure, shaped, and optimum cured at 150° C. for the evaluation of wireadhesion and mechanical properties.

[0078] Cure properties were measured with an Alpha Technologies MDRRheometer at 150° C., 0.5° arc and 1.67 Hz according to ASTM D-5289.Wire pullout adhesion was determined for each test compound by ASTMD-2229-02 using brass plated steel cord with 63.7% copper platingembedded 19 mm into the rubber pad. Table 2 illustrates the curebehavior, wire adhesion, physical and mechanical properties of curedrubber compounds for the methylene acceptor resins of Examples 12 and13. TABLE 2 Rubber Compound Properties Compound Methylene AcceptorExample 13 Example 12 Methylene Donor HMMM HMMM Weight Ratio;Acceptor/Donor, phr 3.0/2.0 3.0/2.0 Mooney Viscosity (212° F.), ML 1 + 465.33 65.16 Rheometer Cure at 150° C. M_(H), dN-m 41.1 40.61 M_(L), dN-m2.89 2.87 t_(S)2, minutes 3.23 3.24 t′90, minutes 25.12 25 WireAdhesion, N (% Rubber Coverage) 3 × 0.2 + 6 × 0.35 wire; 63.72% CuUnaged 1103(90) 1196(85) Steam-aged, 24 Hours at 120° C. 1221(90)1356(90) Humidity-aged, 21 Days, 85° C./95% RH 1119(75) 1246(90) Shore AHardness 88 87 Tensile Properties 100% Modulus, MPa 5.2 5.38 TensileStrength, MPa 24.8 25.4 Elongation, % 440 442 Die-C Tear, KN/m 103 103

[0079] From the Table 2 results, it is clear that the steel wire unaged,heat-, and humidity-aged adhesion properties for the silane-modifiedphenolic resins showed improved performances. Under humidity agedconditions, the rubber coverage on the steel wire showed 90% for thesilane-modified phenolic resin. This data suggest that the use ofsilane-modified phenolic novolak resins in the rubber compounds appearedto enhance the steel wire adhesion with the rubber compounds. Thehumidity aged adhesion enhancement may be due to the protection of thesteel wires from corrosion by the presence of water- ormoisture-resistant phenolic and siloxane cross-linked network structuresat the steel wire and rubber interface.

[0080] As demonstrated above, embodiments of the invention provide asilane-modified phenolic resin for use in rubber compounding. Thesilane-modified phenolic resins have lower softening points andtherefore would enhance the processability of the uncured rubbercompositions which incorporate the resin. However, the improvedprocessability does not compromise other performance properties. Forexample, the adhesion properties and tear properties of the uncuredrubber composition are comparable or better than existing phenolicresins. Accordingly, use of the silane-modified phenolic resin in rubbercompounding should yield better rubber products.

[0081] While the invention has been described with respect to a limitednumber of embodiments, the specific features of one embodiment shouldnot be attributed to other embodiments of the invention. No singleembodiment is representative of all aspects of the invention. In someembodiments, the compositions or methods may include numerous compoundsor steps not mentioned herein. In other embodiments, the compositions ormethods do not include, or are substantially free of, any compounds orsteps not enumerated herein. Variations and modifications from thedescribed embodiments exist. The method of making the resins isdescribed as comprising a number of acts or steps. These steps or actsmay be practiced in any sequence or order unless otherwise indicated.Finally, any number disclosed herein should be construed to meanapproximate, regardless of whether the word “about” or “approximately”is used in describing the number. The appended claims intend to coverall those modifications and variations as falling within the scope ofthe invention.

What is claimed is:
 1. A silane-modified phenolic resin obtained by aprocess comprising reacting a phenolic novolak resin with a silane or amixture of silane compounds represented by Formula (C), (D), or (E):

wherein R₆, R₇ and R₈ are independently an alkyl group of 1 to 4 carbonatoms, an alkoxy group of 1 to 8 carbon atoms, phenyl group, orcycloalkyl group; R₉ is a divalent saturated or unsaturated aliphaticstraight or branched hydrocarbon group with 1 to 12 carbon atoms; X is athiol, isocyanato, urea or glycidylether group; Z is S_(x) or an NHgroup wherein x is 1, 2, 3, 4, 5, 6, 7, or 8; and R₁₀ is a vinyl groupor an alkoxy group, and wherein the silane modified phenolic resin issubstantially free of cross-linking.
 2. The silane-modified phenolicresin of claim 1, wherein the phenolic novolak resin is selected fromphenol-formaldehyde novolak, phenol-alkyl-phenol-formaldehyde novolak,phenol-aralkylphenol-formaldehyde novolak, high orthophenol-formaldehyde novolak, phenol-resorcinol-formaldehyde novolak,alkylphenol-resorcinol-formaldehyde novolak,aralkylphenol-resorcinol-formaldehyde novolak, resorcinol-formaldehydenovolak, alkylresorcinol-formaldehyde novolak,alkyl-resorcinol-resorcinol-formaldehyde novolak,aralkylresorcinol-resorcinol-formaldehyde novolak, or mixtures thereof3. The silane-modified phenolic resin of claim 1, wherein no substantialamount of siloxane polymer is formed during the reaction to make thesilane modified phenolic resin.
 4. The silane-modified phenolic resin ofclaim 1, wherein the phenolic novolak resin is obtained by reacting oneor more phenolic compounds represented by formula (A) with one or morealdehyde or ketone compounds:

wherein R₁, R₂, R₃, R₄ and R₅ represent independently an organic groupselected from hydrogen, hydroxyl, an alkyl having 1 to 15 carbon atoms,an aralkyl having 8 to 12 carbon atoms, halogen or an amino group. 5.The silane-modified phenolic resin of claim 4, wherein the phenoliccompound is a phenol, alkyl substituted phenol, or aralkyl substitutedphenol.
 6. The silane-modified phenolic resin of claim 4, wherein thephenolic compound is a mixture of phenol and alkyl or aryl substitutedphenol.
 7. The silane-modified phenolic resin of claim 4, wherein thephenolic compound is a resorcinol or alkyl substituted resorcinol or anaralkyl substituted resorcinol.
 8. The silane-modified phenolic resin ofclaim 4, wherein the phenolic compound is a mixture of resorcinol andalkyl or aryl substituted resorcinol.
 9. The silane-modified phenolicresin of claim 4, wherein the phenolic compound is a mixture of twocompounds: the first compound is selected from phenol or alkylsubstituted phenol; the second compound is selected from resorcinol oralkyl substituted resorcinol or an aralkyl substituted resorcinol. 10.The silane-modified phenolic resin of claim 4, wherein the phenoliccompound is phenol, o-cresol, m-cresol, p-cresol, o-phenylphenol,p-phenylphenol, 3,5-xylenol, 3,4-xylenol, 3-ethylphenol,3,5-diethylphenol, p-butylphenol, 3,5-dibutylphenol, p-amylphenol,p-cyclohexylphenol, p-octylphenol, p-nonylphenol, styrylphenol,3,5-dicyclohexylphenol, p-crotylphenol, 3,5-dimethoxyphenol,3,4,5-trimethoxyphenol, p-ethoxyphenol, p-butoxyphenol,3-methyl-4-methoxyphenol, p-phenoxyphenol, aminophenol, or mixturesthereof.
 11. The silane-modified phenolic resin of claim 4, wherein thephenolic compound is resorcinol, 5-methylresorcinol, 5-ethylresorcinol,5-propylresorcinol, 2-methylresorcinol, 4-methylresorcinol,4-ethylresorcinol, 4-propylresorcinol, styrylresorcinol, or mixturesthereof.
 12. The silane-modified phenolic resin of claim 4, wherein thephenolic compound is phloroglucinol, pyrogallol, cashew nut shellliquid, or mixtures thereof.
 13. The silane-modified phenolic resin ofclaim 4, wherein the aldehyde is formaldehyde, acetaldehyde,propionaldehyde, butyraldehyde, iso-butyraldehyde, n-valeraldehyde,benzaldehyde, crotonaldehyde, cinnamaldehyde, or mixtures thereof. 14.The silane-modified phenolic resin of claim 1, wherein the silane isrepresented by Formula (C):

wherein R₆, R₇ and R₈ are independently an alkyl group of 1 to 4 carbonatoms, an alkoxy group of 1 to 8 carbon atoms, phenyl group, cycloalkylgroup; R₉ is a divalent saturated or unsaturated aliphatic straight orbranched hydrocarbon group with 1 to 12 carbon atoms; X is a thiol,isocyanato, urea or glycidylether group.
 15. The silane-modifiedphenolic resin of claim 1, wherein the silane is3-(aminopropyl)-triethoxysilane, 3-(isocyanatopropyl)triethoxysilane,3-(glycidyloxypropyl)trimethoxysilane,3-(mercaptopropyl)trimethoxysilane,N-beta-aminoethyl-3-(aminopropyl)trimethoxysilane,3-(aminopropyl)trimethoxysilane, 3-(aminoethyl)triethoxysilane,3-(glycidyloxyethyl)-triethoxysilane, 3-(mercaptopropyl)triethoxysilane,N-beta-aminoethyl-3-(aminoethyl)-trimethoxysilane,3-(aminobutyl)triethoxysilane, 3-(aminoethyl)trimethoxysilane,3-(amino-propyl)methyl-diethoxysilane, N-(3-(triethoxysilyl)propyl)urea,or mixtures thereof.
 16. The silane-modified phenolic resin of claim 1,wherein the silane is represented by Formula (D):

wherein R₆, R₇ and R₈ are independently an alkyl group of 1 to 4 carbonatoms, an alkoxy group of 1 to 8 carbon atoms, phenyl group, cycloalkylgroup; R₉ is a divalent saturated or unsaturated aliphatic straight orbranched hydrocarbon group with 1 to 12 carbon atoms; X is a thiol,isocyanato, urea or glycidylether group; Z is S_(x) or a NH groupwherein x is 1, 2, 3, 4, 5, 6, 7, or
 8. 17. The silane-modified phenolicresin of claim 1, wherein the silane is a bis-silyl polysulfur silane.18. The silane-modified phenolic resin of claim 17, wherein thebis-silyl polysulfur silane is 3,3′-bis(trimethoxysilylpropyl)disulfide,3,3′-bis(triethoxysilylpropyl)tetrasulfide,3,3′-bis(trimethoxysilylpropyl)tetrasulfide,2,2′-bis(triethoxysilylethyl)tetrasulfide,3,3′-bis(trimethoxysilylpropyl)trisulfide,3,3′-bis(triethoxysilylpropyl)trisulfide,3,3′-bis(trimethoxysilylpropyl)hexasulfide,3,3′-bis(trimethoxysilylpropyl)octasulfide,3,3′-bis(trioctoxysilylpropyl)tetrasulfide,3,3′-bis(trihexoxysilylpropyl)disulfide, bis-silyl aminosilanes, ormixtures thereof.
 19. The silane-modified phenolic resin of claim 1,wherein the silane is represented by Formula (E):

wherein R₆, R₇ and R₈ are independently an alkyl group of 1 to 4 carbonatoms, an alkoxy group of 1 to 8 carbon atoms, phenyl group, cycloalkylgroup, and R₁₀ is a vinyl group or an alkoxy group.
 20. Thesilane-modified phenolic resin of claim 1, wherein the silane isvinylmethyldiethoxysilane, vinylmethyldimethoxysilane,vinyltriethoxysilane, vinyltributoxysilane, vinyltriisopropoxysilane,vinyltriisopropenoxysilane, vinyltrimethoxysilane,vinyltriphenoxysilane, vinyltris(2-methoxyethoxy)silane,vinyldimethylethoxysilane, or mixtures thereof.
 21. The silane-modifiedphenolic resin of claim 4, wherein the reaction to make the phenolicnovolak resin further comprises a vinyl aromatic compound.
 22. Thesilane-modified phenolic resin of claim 21, wherein the vinyl aromaticcompound is represented by R₁₁—CH═CH₂, wherein R₁₁ is phenyl orsubstituted phenyl.
 23. The silane-modified phenolic resin of claim 21,wherein the vinyl aromatic compound is styrene, α-methylstyrene,p-methylstyrene, α-chlorostyrene, divinylbenzene, vinyl-naphthalene,indene, or vinyltoluene.
 24. The silane-modified phenolic resin of claim1, wherein the silane-modified phenolic resin is not further hydrolyzed.25. The silane-modified phenolic resin of claim 1, wherein the ratio ofthe number of equivalents of alkoxy groups in the silane compound to thenumber of equivalents of phenolic hydroxyl groups in the phenolicnovolak resin is less than
 1. 26. The silane-modified phenolic resin ofclaim 1, wherein the ratio of the number of equivalents of alkoxy groupsin the silane compound to the number of equivalents of phenolic hydroxylgroups in the phenolic novolak resin is less than 0.1.
 27. Thesilane-modified phenolic resin of claim 1, wherein the ratio of thenumber of equivalents of alkoxy groups in the silane compound to thenumber of equivalents of phenolic hydroxyl groups in the phenolicnovolak resin is less than 0.01.
 28. A rubber compounding agentcomprising the silane-modified phenolic resin of claim
 1. 29. Avulcanizable rubber composition comprising (a) a rubber component, (b) amethylene donor compound which generates formaldehyde by heating; and(c) a methylene acceptor comprising a silane-modified phenolic resinobtained by the process comprising reacting a phenolic novolak resinwith a silane or a mixture of silane compounds represented by Formula(C), (D), or (E):

wherein R₆, R₇ and R₈ are independently an alkyl group of 1 to 4 carbonatoms, an alkoxy group of 1 to 8 carbon atoms, phenyl group, cycloalkylgroup; R₉ is a divalent saturated or unsaturated aliphatic straight orbranched hydrocarbon group with 1 to 12 carbon atoms; X is a thiol,isocyanato, urea or glycidylether group; Z is S_(x) or a NH groupwherein x is 1, 2, 3, 4, 5, 6, 7, or 8; and R₁₀ is a vinyl group or analkoxy group.
 30. The vulcanizable rubber composition of claim 29,wherein the silane-modified phenolic resin is not substantiallycross-linked before the rubber composition is vulcanized.
 31. Thevulcanizable rubber composition of claim 29, wherein no substantialamount of siloxane polymer is formed during the reaction to produce thesilane-modified phenolic resin.
 32. The vulcanizable rubber compositionof claim 29, wherein the rubber component is selected from naturalrubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber,acrylonitrile-butadiene rubber, chloroprene rubber, butyl rubber,halogenated butyl rubber, ethylene-propylene-diene monomer (EPDM)rubber, or mixtures thereof.
 33. The vulcanizable rubber composition ofclaim 29, further comprising a reinforcing material selected from steel,polyester, nylon, aramid, fiberglass, or a combination thereof.
 34. Thevulcanizable rubber composition of claim 32, wherein the reinforcingmaterial is a steel cord coated by brass, zinc or bronze.
 35. Afabricated article comprising the vulcanizable rubber composition ofclaim
 29. 36. The fabricated article of claim 35, wherein the fabricatedarticle is a tire, a power belt, a conveyor belt, a printing roll, arubber shoe heel, a rubber shoe sole, an automobile floor mat, a truckmud flap, or a ball mill liner.
 37. A method of making a fabricatedrubber article, comprising: obtaining a vulcanizable rubber compositionof claim 29 mixed with a cross-linking agent; embedding a reinforcingmaterial in the vulcanizable rubber composition; and effectingcross-linking of the rubber composition, wherein the reinforcingmaterial is embedded in the rubber composition before the cross-linkingand is substantially free of a silane coating before the embedding. 38.The method of claim 37, wherein the reinforcing material is selectedfrom steel, polyester, nylon, aramid, fiberglass, or a combinationthereof.
 39. The method of claim 37, wherein the reinforcing material isin the form of wire or cord.